Devices are known that may be implanted within a patient's body to monitor one or more physiological conditions and/or to provide therapeutic functions. For example, sensors or transducers may be located deep within the body for monitoring a variety of properties, such as temperature, pressure, strain, fluid flow, chemical properties, electrical properties, magnetic properties, and the like. In addition, devices may be implanted that perform one or more therapeutic functions, such as drug delivery, defibrillation, electrical stimulation, and the like. Often it is desirable to control or otherwise communicate with such devices once they are implanted within a patient, for example, to obtain data, and/or to activate or deactivate the implanted device.
Various methods for activating and communicating with implants have been suggested. Most relevant to the current invention is the activation, controlling and communication with implants using acoustic energy, as described by Penner and Doron in U.S. Pat. No. 7,198,603, entitled “Apparatus and Methods Using Acoustic Telemetry for Intrabody Communications,” which is expressly incorporated herein by reference. In U.S. Pat. No. 7,024,248 entitled “Systems and Methods For Communicating with Implantable Devices,” which is expressly incorporated herein by reference, the same inventors described systems and methods for communicating with an implant within a patient's body using acoustic telemetry based on an external communications device attachable to the patient's skin. Significantly, because other forms of energy, such as radio frequency (RF) energy, can only penetrate a few millimeters into a body due to the dielectric nature of tissue, wirelessly communicating using acoustic energy, which does not significantly attenuate when traveling through tissue, lends itself well to implementations where it is desirable to communicate with a device that has been implanted deep within the tissue.
It is sometimes desirable to wirelessly communicate between implanted devices. For example, U.S. Patent Publication No. 2005/0288727, entitled “Wireless Sensing Devices for Evaluating Heart Performance,” which is expressly incorporated herein by reference, describes a system for evaluating the performance and status of a heart and optionally providing therapy to the heart based on the evaluation. In this exemplary system, diagnostic devices, such as accelerometers, strain gauges, or tactile sensors, are implanted within various locations of the heart to measure certain characteristics of the heart, e.g., contractility or movement. One or more therapeutic devices, such as a drug pump, implantable pulse generator (IPG) (e.g., pacemaker, implantable cardioverter defibrillator (ICD), or cardiac resynchronization therapy (CRT) device, such as a CRT-P (pacemaker) or CRT-D (defibrillator)), or nerve simulator, can be implanted within the appropriate region of the body. The operation of the therapeutic device(s) may then be controlled or optimized based on the information received from the diagnostic devices.
While direct wireless communication between implanted devices works in theory, this implementation has drawbacks. For example, to enable direct wireless communication between two implantable devices, both devices should have the same means of communication, e.g., both should either wirelessly communicate acoustically or wirelessly communicate electromagnetically. Thus, in the case where it is desirable that the diagnostic device be equipped with an acoustic means of communication, e.g., if it is to be implanted deep with the patient's body, than a therapeutic device that directly communicates with the diagnostic device should likewise be equipped with a similar acoustic means of communications. However, this requires a significant modification to existing therapeutic devices (which oftentimes use electromagnetic energy to wirelessly communicate), including modification of an on-board integrated circuit (IC) and software, incorporation of an acoustic transducer, and several other changes. Such changes will lead to an increase in the size and energy consumption of the therapeutic device, as well as the need to revalidate the therapeutic device—a tedious task that the manufacturer/distributor of the therapeutic device would rather avoid.
There thus is a need to provide an improved system that allows two or more implantable devices to interact with each other.